With the development of the industry of touch screens, the touch screens have been required to tend to be frameless.
At present, signal transmission lines in a frame around a touch screen are usually made of a metal. Metal wires have good electrical conductivity, a small line width and a low resistance, and can meet the requirement of a narrow frame. However, since metals are not transparent, it is impossible to realize the framelessness of the touch screen by making the signal transmission lines using metal wires. In addition, ITO and other transparent conductive thin films have relatively high visible light transmittance but a relatively large resistance, and thus cannot be used to make the signal transmission lines of the touch screens.
Currently, only a narrow frame of the touch screen can be realized. To be specific, for a touch screen of a mobile phone, its frame has a width which may be controlled within a range of 2 to 3 mm; for a touch screen of a TPC (Touch PC)/NB (Notebook), its frame has a width which may be controlled to be around 5 mm; and for a touch screen of a MNT (a professional display), its frame has a width which may be controlled to be around 10 mm. But there is no technology that can realize the framelessness of the touch screen at present.